The present invention relates to a rotor for an electric machine and an electric machine with a stator and a rotor.
Electric machines of this type with movable units in the form of rotors are known in the prior art in principle, obviating the need for separate documentary evidence. In principle, a stator is provided for a rotating electric machine which as a rule provides an essentially circular aperture for receiving a rotor designed as a rotor. The rotor can be pivoted in the aperture, an air gap being formed between the rotor and the stator.
Furthermore, there are electric machines for linear operation in which the stator is at least partially designed along a line of movement or movement curve for a rotor designed as a translator. The translator interacts with the stator and is flexibly arranged along the line of movement and/or the movement curve. The translator is moved along the stator and/or the line of movement by means of controlled magnetic action.
A rotor for the purposes of this disclosure is therefore a movable unit which for a rotating electric machine is designed in the form of a rotor and for an electric machine for linear operation as a translator. As a rule, the stator is stationary with regard to a device or a base plate connected to the ground. In the case of a vehicle, the stator may be connected, for example, to a chassis, an undercarriage or the like, stationary being understood to mean with regard to the device or the base plate. The rotor thus forms the movable unit with regard to the stator.
In particular, in the case of rotating electric machines which are intended for use as torque motors, but also in the case of linear motors for direct drive applications, permanent magnets are frequently used with the rotor. In order to be able to generate the major force desired, as a rule such magnets are sintered rare earth magnets. Due to the high costs of such magnets, such machines are therefore only used in special cases for which such an investment can be adequately justified. There are many applications, however, for which such machines could likewise be used expediently but are not due to the high cost. There is therefore a need for alternatives to replace expensive rare earth magnets, in particular, NdFeB sintered magnets, for example.
One approach provides for the replacement of such magnets with ferrite magnets. It has been shown that compared to rare earth magnets, ferrite magnets have a substantially lower energy density, that is to say, they provide a lower magnetic flux, and—for example, due to the large dimensions required—cannot be put to practical use with the usual structures envisaged.